If you're used to either iCal or Google Calendar then it's a shame to have to choose between the two. Both are great organizational tools in different ways.

Calaboration lets you have it all by allowing you to keep both iCal and Google Calendar in sync so you never need to choose between using one or the other again. And it works absolutely seamlessly. All changes you make in either iCal or Google Calendar are synced in real-time (assuming of course that you are connected to the internet). If you're not, then the two applications will update the next time you are connected.

Setup is extremely easy. You're asked to enter your Google Account username and password so that iCal and sync with it. You're also asked if you want to add the e-mail address you've supplied to be added to your iCal contacts. From them on, it's plain sailing. Simply add and change appointments in either app and the two update simultaneously.

There's little to fault with Calaboration. It does a simple but effective job of meaning your iCal and Google Calendar appointments and reminders are always in sync.